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authorYann Collet <cyan@fb.com>2018-09-11 17:01:33 (GMT)
committerYann Collet <cyan@fb.com>2018-09-11 17:01:33 (GMT)
commit90865b80aa9ae1f19a47f8742f5bcd38f0e24b0a (patch)
tree2e4f1bb6f3f3ec035365e441079e37aed43e153d
parent86ad9131db3fc0c1839e791d8345095487ca4dad (diff)
parent82a693c1365ca30a99c620c3f157847bef65d46f (diff)
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Merge branch 'dev' of github.com:Cyan4973/lz4 into dev
-rw-r--r--doc/lz4_manual.html105
-rw-r--r--lib/lz4.c143
-rw-r--r--lib/lz4.h36
-rw-r--r--tests/fullbench.c32
-rw-r--r--tests/fuzzer.c22
5 files changed, 215 insertions, 123 deletions
diff --git a/doc/lz4_manual.html b/doc/lz4_manual.html
index c7c5763..6ebf8d2 100644
--- a/doc/lz4_manual.html
+++ b/doc/lz4_manual.html
@@ -110,45 +110,67 @@ int LZ4_compress_fast_extState (void* state, const char* src, char* dst, int src
</b><p> Same compression function, just using an externally allocated memory space to store compression state.
Use LZ4_sizeofState() to know how much memory must be allocated,
and allocate it on 8-bytes boundaries (using malloc() typically).
- Then, provide it as 'void* state' to compression function.
+ Then, provide this buffer as 'void* state' to compression function.
</p></pre><BR>
<pre><b>int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePtr, int targetDstSize);
-</b><p> Reverse the logic : compresses as much data as possible from 'src' buffer
- into already allocated buffer 'dst' of size 'targetDestSize'.
- This function either compresses the entire 'src' content into 'dst' if it's large enough,
- or fill 'dst' buffer completely with as much data as possible from 'src'.
- *srcSizePtr : will be modified to indicate how many bytes where read from 'src' to fill 'dst'.
- New value is necessarily <= old value.
- return : Nb bytes written into 'dst' (necessarily <= targetDestSize)
- or 0 if compression fails
+</b><p> Reverse the logic : compresses as much data as possible from 'src' buffer
+ into already allocated buffer 'dst', of size >= 'targetDestSize'.
+ This function either compresses the entire 'src' content into 'dst' if it's large enough,
+ or fill 'dst' buffer completely with as much data as possible from 'src'.
+ note: acceleration parameter is fixed to "default".
+
+ *srcSizePtr : will be modified to indicate how many bytes where read from 'src' to fill 'dst'.
+ New value is necessarily <= input value.
+ @return : Nb bytes written into 'dst' (necessarily <= targetDestSize)
+ or 0 if compression fails.
</p></pre><BR>
<pre><b>int LZ4_decompress_fast (const char* src, char* dst, int originalSize);
-</b><p>This function is a bit faster than LZ4_decompress_safe(),
-but it may misbehave on malformed input because it doesn't perform full validation of compressed data.
- originalSize : is the uncompressed size to regenerate
- Destination buffer must be already allocated, and its size must be >= 'originalSize' bytes.
- return : number of bytes read from source buffer (== compressed size).
- If the source stream is detected malformed, the function stops decoding and return a negative result.
- note : This function is only usable if the originalSize of uncompressed data is known in advance.
- The caller should also check that all the compressed input has been consumed properly,
- i.e. that the return value matches the size of the buffer with compressed input.
- The function never writes past the output buffer. However, since it doesn't know its 'src' size,
- it may read past the intended input. Also, because match offsets are not validated during decoding,
- reads from 'src' may underflow. Use this function in trusted environment **only**.
+</b><p> This function used to be a bit faster than LZ4_decompress_safe(),
+ though situation has changed in recent versions,
+ and now `LZ4_decompress_safe()` can be as fast and sometimes faster than `LZ4_decompress_fast()`.
+ Moreover, LZ4_decompress_fast() is not protected vs malformed input, as it doesn't perform full validation of compressed data.
+ As a consequence, this function is no longer recommended, and may be deprecated in future versions.
+ It's only remaining specificity is that it can decompress data without knowing its compressed size.
+
+ originalSize : is the uncompressed size to regenerate.
+ `dst` must be already allocated, its size must be >= 'originalSize' bytes.
+ @return : number of bytes read from source buffer (== compressed size).
+ If the source stream is detected malformed, the function stops decoding and returns a negative result.
+ note : This function requires uncompressed originalSize to be known in advance.
+ The function never writes past the output buffer.
+ However, since it doesn't know its 'src' size, it may read past the intended input.
+ Also, because match offsets are not validated during decoding,
+ reads from 'src' may underflow.
+ Use this function in trusted environment **only**.
+
</p></pre><BR>
<pre><b>int LZ4_decompress_safe_partial (const char* src, char* dst, int srcSize, int targetOutputSize, int dstCapacity);
-</b><p> This function decompress a compressed block of size 'srcSize' at position 'src'
- into destination buffer 'dst' of size 'dstCapacity'.
- The function will decompress a minimum of 'targetOutputSize' bytes, and stop after that.
- However, it's not accurate, and may write more than 'targetOutputSize' (but always <= dstCapacity).
- @return : the number of bytes decoded in the destination buffer (necessarily <= dstCapacity)
- Note : this number can also be < targetOutputSize, if compressed block contains less data.
- Therefore, always control how many bytes were decoded.
- If source stream is detected malformed, function returns a negative result.
- This function is protected against malicious data packets.
+</b><p> Decompress an LZ4 compressed block, of size 'srcSize' at position 'src',
+ into destination buffer 'dst' of size 'dstCapacity'.
+ Up to 'targetOutputSize' bytes will be decoded.
+ The function stops decoding on reaching this objective,
+ which can boost performance when only the beginning of a block is required.
+
+ @return : the number of bytes decoded in `dst` (necessarily <= dstCapacity)
+ If source stream is detected malformed, function returns a negative result.
+
+ Note : @return can be < targetOutputSize, if compressed block contains less data.
+
+ Note 2 : this function features 2 parameters, targetOutputSize and dstCapacity,
+ and expects targetOutputSize <= dstCapacity.
+ It effectively stops decoding on reaching targetOutputSize,
+ so dstCapacity is kind of redundant.
+ This is because in a previous version of this function,
+ decoding operation would not "break" a sequence in the middle.
+ As a consequence, there was no guarantee that decoding would stop at exactly targetOutputSize,
+ it could write more bytes, though only up to dstCapacity.
+ Some "margin" used to be required for this operation to work properly.
+ This is no longer necessary.
+ The function nonetheless keeps its signature, in an effort to not break API.
+
</p></pre><BR>
<a name="Chapter6"></a><h2>Streaming Compression Functions</h2><pre></pre>
@@ -179,16 +201,23 @@ int LZ4_freeStream (LZ4_stream_t* streamPtr);
'dst' buffer must be already allocated.
If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.
- Important : The previous 64KB of source data is assumed to remain present and unmodified in memory!
-
- Special 1 : When input is a double-buffer, they can have any size, including < 64 KB.
- Make sure that buffers are separated by at least one byte.
- This way, each block only depends on previous block.
- Special 2 : If input buffer is a ring-buffer, it can have any size, including < 64 KB.
-
@return : size of compressed block
or 0 if there is an error (typically, cannot fit into 'dst').
- After an error, the stream status is invalid, it can only be reset or freed.
+
+ Note 1 : Each invocation to LZ4_compress_fast_continue() generates a new block.
+ Each block has precise boundaries.
+ It's not possible to append blocks together and expect a single invocation of LZ4_decompress_*() to decompress them together.
+ Each block must be decompressed separately, calling LZ4_decompress_*() with associated metadata.
+
+ Note 2 : The previous 64KB of source data is __assumed__ to remain present, unmodified, at same address in memory!
+
+ Note 3 : When input is structured as a double-buffer, each buffer can have any size, including < 64 KB.
+ Make sure that buffers are separated, by at least one byte.
+ This construction ensures that each block only depends on previous block.
+
+ Note 4 : If input buffer is a ring-buffer, it can have any size, including < 64 KB.
+
+ Note 5 : After an error, the stream status is invalid, it can only be reset or freed.
</p></pre><BR>
diff --git a/lib/lz4.c b/lib/lz4.c
index 35df7f5..4046102 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -1,6 +1,6 @@
/*
LZ4 - Fast LZ compression algorithm
- Copyright (C) 2011-2017, Yann Collet.
+ Copyright (C) 2011-present, Yann Collet.
BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
@@ -297,8 +297,9 @@ void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd)
#define MINMATCH 4
#define WILDCOPYLENGTH 8
-#define LASTLITERALS 5
-#define MFLIMIT (WILDCOPYLENGTH+MINMATCH)
+#define LASTLITERALS 5 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
+#define MFLIMIT 12 /* see ../doc/lz4_Block_format.md#parsing-restrictions */
+#define MATCH_SAFEGUARD_DISTANCE ((2*WILDCOPYLENGTH) - MINMATCH) /* ensure it's possible to write 2 x wildcopyLength without overflowing output buffer */
static const int LZ4_minLength = (MFLIMIT+1);
#define KB *(1 <<10)
@@ -483,9 +484,6 @@ typedef enum { clearedTable = 0, byPtr, byU32, byU16 } tableType_t;
typedef enum { noDict = 0, withPrefix64k, usingExtDict, usingDictCtx } dict_directive;
typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
-typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
-typedef enum { full = 0, partial = 1 } earlyEnd_directive;
-
/*-************************************
* Local Utils
@@ -684,9 +682,9 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
/* the dictCtx currentOffset is indexed on the start of the dictionary,
* while a dictionary in the current context precedes the currentOffset */
- const BYTE* dictBase = dictDirective == usingDictCtx ?
- dictionary + dictSize - dictCtx->currentOffset :
- dictionary + dictSize - startIndex;
+ const BYTE* dictBase = (dictDirective == usingDictCtx) ?
+ dictionary + dictSize - dictCtx->currentOffset :
+ dictionary + dictSize - startIndex;
BYTE* op = (BYTE*) dest;
BYTE* const olimit = op + maxOutputSize;
@@ -1385,9 +1383,16 @@ int LZ4_saveDict (LZ4_stream_t* LZ4_dict, char* safeBuffer, int dictSize)
-/*-*****************************
-* Decompression functions
-*******************************/
+/*-*******************************
+ * Decompression functions
+ ********************************/
+
+typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
+typedef enum { decode_full_block = 0, partial_decode = 1 } earlyEnd_directive;
+
+#undef MIN
+#define MIN(a,b) ( (a) < (b) ? (a) : (b) )
+
/*! LZ4_decompress_generic() :
* This generic decompression function covers all use cases.
* It shall be instantiated several times, using different sets of directives.
@@ -1401,10 +1406,9 @@ LZ4_decompress_generic(
int srcSize,
int outputSize, /* If endOnInput==endOnInputSize, this value is `dstCapacity` */
- int endOnInput, /* endOnOutputSize, endOnInputSize */
- int partialDecoding, /* full, partial */
- int targetOutputSize, /* only used if partialDecoding==partial */
- int dict, /* noDict, withPrefix64k, usingExtDict */
+ endCondition_directive endOnInput, /* endOnOutputSize, endOnInputSize */
+ earlyEnd_directive partialDecoding, /* full, partial */
+ dict_directive dict, /* noDict, withPrefix64k, usingExtDict */
const BYTE* const lowPrefix, /* always <= dst, == dst when no prefix */
const BYTE* const dictStart, /* only if dict==usingExtDict */
const size_t dictSize /* note : = 0 if noDict */
@@ -1416,7 +1420,6 @@ LZ4_decompress_generic(
BYTE* op = (BYTE*) dst;
BYTE* const oend = op + outputSize;
BYTE* cpy;
- BYTE* oexit = op + targetOutputSize;
const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize;
const unsigned inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4};
@@ -1429,12 +1432,13 @@ LZ4_decompress_generic(
const BYTE* const shortiend = iend - (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/;
const BYTE* const shortoend = oend - (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/;
- DEBUGLOG(5, "LZ4_decompress_generic (srcSize:%i)", srcSize);
+ DEBUGLOG(5, "LZ4_decompress_generic (srcSize:%i, dstSize:%i)", srcSize, outputSize);
/* Special cases */
- if ((partialDecoding) && (oexit > oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => just decode everything */
+ assert(lowPrefix <= op);
+ assert(src != NULL);
if ((endOnInput) && (unlikely(outputSize==0))) return ((srcSize==1) && (*ip==0)) ? 0 : -1; /* Empty output buffer */
- if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
+ if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0 ? 1 : -1);
if ((endOnInput) && unlikely(srcSize==0)) return -1;
/* Main Loop : decode sequences */
@@ -1443,7 +1447,7 @@ LZ4_decompress_generic(
size_t offset;
unsigned const token = *ip++;
- size_t length = token >> ML_BITS; /* literal length */
+ size_t length = token >> ML_BITS; /* literal length */
assert(!endOnInput || ip <= iend); /* ip < iend before the increment */
@@ -1468,6 +1472,7 @@ LZ4_decompress_generic(
length = token & ML_MASK; /* match length */
offset = LZ4_readLE16(ip); ip += 2;
match = op - offset;
+ assert(match <= op); /* check overflow */
/* Do not deal with overlapping matches. */
if ( (length != ML_MASK)
@@ -1501,11 +1506,12 @@ LZ4_decompress_generic(
/* copy literals */
cpy = op+length;
- if ( ((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) )
- || ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) )
+ LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH);
+ if ( ((endOnInput) && ((cpy>oend-MFLIMIT) || (ip+length>iend-(2+1+LASTLITERALS))) )
+ || ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) )
{
if (partialDecoding) {
- if (cpy > oend) goto _output_error; /* Error : write attempt beyond end of output buffer */
+ if (cpy > oend) { cpy = oend; length = oend-op; } /* Partial decoding : stop in the middle of literal segment */
if ((endOnInput) && (ip+length > iend)) goto _output_error; /* Error : read attempt beyond end of input buffer */
} else {
if ((!endOnInput) && (cpy != oend)) goto _output_error; /* Error : block decoding must stop exactly there */
@@ -1514,10 +1520,15 @@ LZ4_decompress_generic(
memcpy(op, ip, length);
ip += length;
op += length;
- break; /* Necessarily EOF, due to parsing restrictions */
+ if (!partialDecoding || (cpy == oend)) {
+ /* Necessarily EOF, due to parsing restrictions */
+ break;
+ }
+
+ } else {
+ LZ4_wildCopy(op, ip, cpy); /* may overwrite up to WILDCOPYLENGTH beyond cpy */
+ ip += length; op = cpy;
}
- LZ4_wildCopy(op, ip, cpy);
- ip += length; op = cpy;
/* get offset */
offset = LZ4_readLE16(ip); ip+=2;
@@ -1528,7 +1539,11 @@ LZ4_decompress_generic(
_copy_match:
if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) goto _output_error; /* Error : offset outside buffers */
- LZ4_write32(op, (U32)offset); /* costs ~1%; silence an msan warning when offset==0 */
+ if (!partialDecoding) {
+ assert(oend > op);
+ assert(oend - op >= 4);
+ LZ4_write32(op, 0); /* silence an msan warning when offset==0; costs <1%; */
+ } /* note : when partialDecoding, there is no guarantee that at least 4 bytes remain available in output buffer */
if (length == ML_MASK) {
unsigned s;
@@ -1541,21 +1556,24 @@ _copy_match:
}
length += MINMATCH;
- /* check external dictionary */
+ /* match starting within external dictionary */
if ((dict==usingExtDict) && (match < lowPrefix)) {
- if (unlikely(op+length > oend-LASTLITERALS)) goto _output_error; /* doesn't respect parsing restriction */
+ if (unlikely(op+length > oend-LASTLITERALS)) {
+ if (partialDecoding) length = MIN(length, (size_t)(oend-op));
+ else goto _output_error; /* doesn't respect parsing restriction */
+ }
if (length <= (size_t)(lowPrefix-match)) {
- /* match can be copied as a single segment from external dictionary */
+ /* match fits entirely within external dictionary : just copy */
memmove(op, dictEnd - (lowPrefix-match), length);
op += length;
} else {
- /* match encompass external dictionary and current block */
- size_t const copySize = (size_t)(lowPrefix-match);
+ /* match stretches into both external dictionary and current block */
+ size_t const copySize = (size_t)(lowPrefix - match);
size_t const restSize = length - copySize;
memcpy(op, dictEnd - copySize, copySize);
op += copySize;
- if (restSize > (size_t)(op-lowPrefix)) { /* overlap copy */
+ if (restSize > (size_t)(op - lowPrefix)) { /* overlap copy */
BYTE* const endOfMatch = op + restSize;
const BYTE* copyFrom = lowPrefix;
while (op < endOfMatch) *op++ = *copyFrom++;
@@ -1568,6 +1586,23 @@ _copy_match:
/* copy match within block */
cpy = op + length;
+
+ /* partialDecoding : may not respect endBlock parsing restrictions */
+ assert(op<=oend);
+ if (partialDecoding && (cpy > oend-MATCH_SAFEGUARD_DISTANCE)) {
+ size_t const mlen = MIN(length, (size_t)(oend-op));
+ const BYTE* const matchEnd = match + mlen;
+ BYTE* const copyEnd = op + mlen;
+ if (matchEnd > op) { /* overlap copy */
+ while (op < copyEnd) *op++ = *match++;
+ } else {
+ memcpy(op, match, mlen);
+ }
+ op = copyEnd;
+ if (op==oend) break;
+ continue;
+ }
+
if (unlikely(offset<8)) {
op[0] = match[0];
op[1] = match[1];
@@ -1576,23 +1611,26 @@ _copy_match:
match += inc32table[offset];
memcpy(op+4, match, 4);
match -= dec64table[offset];
- } else { memcpy(op, match, 8); match+=8; }
+ } else {
+ memcpy(op, match, 8);
+ match += 8;
+ }
op += 8;
- if (unlikely(cpy>oend-12)) {
- BYTE* const oCopyLimit = oend-(WILDCOPYLENGTH-1);
+ if (unlikely(cpy > oend-MATCH_SAFEGUARD_DISTANCE)) {
+ BYTE* const oCopyLimit = oend - (WILDCOPYLENGTH-1);
if (cpy > oend-LASTLITERALS) goto _output_error; /* Error : last LASTLITERALS bytes must be literals (uncompressed) */
if (op < oCopyLimit) {
LZ4_wildCopy(op, match, oCopyLimit);
match += oCopyLimit - op;
op = oCopyLimit;
}
- while (op<cpy) *op++ = *match++;
+ while (op < cpy) *op++ = *match++;
} else {
memcpy(op, match, 8);
- if (length>16) LZ4_wildCopy(op+8, match+8, cpy);
+ if (length > 16) LZ4_wildCopy(op+8, match+8, cpy);
}
- op = cpy; /* correction */
+ op = cpy; /* wildcopy correction */
}
/* end of decoding */
@@ -1613,23 +1651,24 @@ LZ4_FORCE_O2_GCC_PPC64LE
int LZ4_decompress_safe(const char* source, char* dest, int compressedSize, int maxDecompressedSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxDecompressedSize,
- endOnInputSize, full, 0, noDict,
+ endOnInputSize, decode_full_block, noDict,
(BYTE*)dest, NULL, 0);
}
LZ4_FORCE_O2_GCC_PPC64LE
-int LZ4_decompress_safe_partial(const char* source, char* dest, int compressedSize, int targetOutputSize, int maxDecompressedSize)
+int LZ4_decompress_safe_partial(const char* src, char* dst, int compressedSize, int targetOutputSize, int dstCapacity)
{
- return LZ4_decompress_generic(source, dest, compressedSize, maxDecompressedSize,
- endOnInputSize, partial, targetOutputSize,
- noDict, (BYTE*)dest, NULL, 0);
+ dstCapacity = MIN(targetOutputSize, dstCapacity);
+ return LZ4_decompress_generic(src, dst, compressedSize, dstCapacity,
+ endOnInputSize, partial_decode,
+ noDict, (BYTE*)dst, NULL, 0);
}
LZ4_FORCE_O2_GCC_PPC64LE
int LZ4_decompress_fast(const char* source, char* dest, int originalSize)
{
return LZ4_decompress_generic(source, dest, 0, originalSize,
- endOnOutputSize, full, 0, withPrefix64k,
+ endOnOutputSize, decode_full_block, withPrefix64k,
(BYTE*)dest - 64 KB, NULL, 0);
}
@@ -1639,7 +1678,7 @@ LZ4_FORCE_O2_GCC_PPC64LE /* Exported, an obsolete API function. */
int LZ4_decompress_safe_withPrefix64k(const char* source, char* dest, int compressedSize, int maxOutputSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, full, 0, withPrefix64k,
+ endOnInputSize, decode_full_block, withPrefix64k,
(BYTE*)dest - 64 KB, NULL, 0);
}
@@ -1656,7 +1695,7 @@ static int LZ4_decompress_safe_withSmallPrefix(const char* source, char* dest, i
size_t prefixSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, full, 0, noDict,
+ endOnInputSize, decode_full_block, noDict,
(BYTE*)dest-prefixSize, NULL, 0);
}
@@ -1666,7 +1705,7 @@ int LZ4_decompress_safe_forceExtDict(const char* source, char* dest,
const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, full, 0, usingExtDict,
+ endOnInputSize, decode_full_block, usingExtDict,
(BYTE*)dest, (const BYTE*)dictStart, dictSize);
}
@@ -1675,7 +1714,7 @@ static int LZ4_decompress_fast_extDict(const char* source, char* dest, int origi
const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, 0, originalSize,
- endOnOutputSize, full, 0, usingExtDict,
+ endOnOutputSize, decode_full_block, usingExtDict,
(BYTE*)dest, (const BYTE*)dictStart, dictSize);
}
@@ -1688,7 +1727,7 @@ int LZ4_decompress_safe_doubleDict(const char* source, char* dest, int compresse
size_t prefixSize, const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
- endOnInputSize, full, 0, usingExtDict,
+ endOnInputSize, decode_full_block, usingExtDict,
(BYTE*)dest-prefixSize, (const BYTE*)dictStart, dictSize);
}
@@ -1697,7 +1736,7 @@ int LZ4_decompress_fast_doubleDict(const char* source, char* dest, int originalS
size_t prefixSize, const void* dictStart, size_t dictSize)
{
return LZ4_decompress_generic(source, dest, 0, originalSize,
- endOnOutputSize, full, 0, usingExtDict,
+ endOnOutputSize, decode_full_block, usingExtDict,
(BYTE*)dest-prefixSize, (const BYTE*)dictStart, dictSize);
}
diff --git a/lib/lz4.h b/lib/lz4.h
index 9d3890a..059ef7c 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -1,7 +1,7 @@
/*
* LZ4 - Fast LZ compression algorithm
* Header File
- * Copyright (C) 2011-2017, Yann Collet.
+ * Copyright (C) 2011-present, Yann Collet.
BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
@@ -46,7 +46,7 @@ extern "C" {
/**
Introduction
- LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core,
+ LZ4 is lossless compression algorithm, providing compression speed at 500 MB/s per core,
scalable with multi-cores CPU. It features an extremely fast decoder, with speed in
multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
@@ -62,8 +62,8 @@ extern "C" {
An additional format, called LZ4 frame specification (doc/lz4_Frame_format.md),
take care of encoding standard metadata alongside LZ4-compressed blocks.
- If your application requires interoperability, it's recommended to use it.
- A library is provided to take care of it, see lz4frame.h.
+ Frame format is required for interoperability.
+ It is delivered through a companion API, declared in lz4frame.h.
*/
/*^***************************************************************
@@ -226,14 +226,28 @@ LZ4LIB_API int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePt
LZ4LIB_API int LZ4_decompress_fast (const char* src, char* dst, int originalSize);
/*! LZ4_decompress_safe_partial() :
- * This function decompresses a compressed block of size 'srcSize' at position 'src'
+ * Decompress an LZ4 compressed block, of size 'srcSize' at position 'src',
* into destination buffer 'dst' of size 'dstCapacity'.
- * The function will decompress a minimum of 'targetOutputSize' bytes, and stop after that.
- * However, it's not accurate, and may write more than 'targetOutputSize' (but always <= dstCapacity).
+ * Up to 'targetOutputSize' bytes will be decoded.
+ * The function stops decoding on reaching this objective,
+ * which can boost performance when only the beginning of a block is required.
+ *
* @return : the number of bytes decoded in `dst` (necessarily <= dstCapacity)
- * Note : this number can also be < targetOutputSize, if compressed block contains less data.
* If source stream is detected malformed, function returns a negative result.
- * This function is protected against malicious data packets.
+ *
+ * Note : @return can be < targetOutputSize, if compressed block contains less data.
+ *
+ * Note 2 : this function features 2 parameters, targetOutputSize and dstCapacity,
+ * and expects targetOutputSize <= dstCapacity.
+ * It effectively stops decoding on reaching targetOutputSize,
+ * so dstCapacity is kind of redundant.
+ * This is because in a previous version of this function,
+ * decoding operation would not "break" a sequence in the middle.
+ * As a consequence, there was no guarantee that decoding would stop at exactly targetOutputSize,
+ * it could write more bytes, though only up to dstCapacity.
+ * Some "margin" used to be required for this operation to work properly.
+ * This is no longer necessary.
+ * The function nonetheless keeps its signature, in an effort to not break API.
*/
LZ4LIB_API int LZ4_decompress_safe_partial (const char* src, char* dst, int srcSize, int targetOutputSize, int dstCapacity);
@@ -272,12 +286,12 @@ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, in
* @return : size of compressed block
* or 0 if there is an error (typically, cannot fit into 'dst').
*
- * Note 1 : Each invocation to LZ4_compress_fast_continue() will generate a new block.
+ * Note 1 : Each invocation to LZ4_compress_fast_continue() generates a new block.
* Each block has precise boundaries.
* It's not possible to append blocks together and expect a single invocation of LZ4_decompress_*() to decompress them together.
* Each block must be decompressed separately, calling LZ4_decompress_*() with associated metadata.
*
- * Note 2 : The previous 64KB of source data is assumed to remain present, unmodified, at same address in memory!
+ * Note 2 : The previous 64KB of source data is __assumed__ to remain present, unmodified, at same address in memory!
*
* Note 3 : When input is structured as a double-buffer, each buffer can have any size, including < 64 KB.
* Make sure that buffers are separated, by at least one byte.
diff --git a/tests/fullbench.c b/tests/fullbench.c
index 2818ea2..fd1202d 100644
--- a/tests/fullbench.c
+++ b/tests/fullbench.c
@@ -317,7 +317,9 @@ static int local_LZ4_decompress_safe_forceExtDict(const char* in, char* out, int
static int local_LZ4_decompress_safe_partial(const char* in, char* out, int inSize, int outSize)
{
- return LZ4_decompress_safe_partial(in, out, inSize, outSize - 5, outSize);
+ int result = LZ4_decompress_safe_partial(in, out, inSize, outSize - 5, outSize);
+ if (result < 0) return result;
+ return outSize;
}
@@ -462,9 +464,9 @@ int fullSpeedBench(const char** fileNamesTable, int nbFiles)
case 12: compressionFunction = local_LZ4_compress_HC_extStateHC; compressorName = "LZ4_compress_HC_extStateHC"; break;
case 14: compressionFunction = local_LZ4_compress_HC_continue; initFunction = local_LZ4_resetStreamHC; compressorName = "LZ4_compress_HC_continue"; break;
#ifndef LZ4_DLL_IMPORT
- case 20: compressionFunction = local_LZ4_compress_forceDict; initFunction = local_LZ4_resetDictT; compressorName = "LZ4_compress_forceDict"; break;
+ case 20: compressionFunction = local_LZ4_compress_forceDict; initFunction = local_LZ4_resetDictT; compressorName = "LZ4_compress_forceDict"; break;
#endif
- case 30: compressionFunction = local_LZ4F_compressFrame; compressorName = "LZ4F_compressFrame";
+ case 30: compressionFunction = local_LZ4F_compressFrame; compressorName = "LZ4F_compressFrame";
chunkP[0].origSize = (int)benchedSize; nbChunks=1;
break;
case 40: compressionFunction = local_LZ4_saveDict; compressorName = "LZ4_saveDict";
@@ -542,6 +544,7 @@ int fullSpeedBench(const char** fileNamesTable, int nbFiles)
const char* dName;
int (*decompressionFunction)(const char*, char*, int, int);
double bestTime = 100000000.;
+ int checkResult = 1;
if ((g_decompressionAlgo != ALL_DECOMPRESSORS) && (g_decompressionAlgo != dAlgNb)) continue;
@@ -553,11 +556,11 @@ int fullSpeedBench(const char** fileNamesTable, int nbFiles)
case 3: decompressionFunction = local_LZ4_decompress_fast_usingExtDict; dName = "LZ4_decompress_fast_using(Ext)Dict"; break;
case 4: decompressionFunction = LZ4_decompress_safe; dName = "LZ4_decompress_safe"; break;
case 6: decompressionFunction = local_LZ4_decompress_safe_usingDict; dName = "LZ4_decompress_safe_usingDict"; break;
- case 7: decompressionFunction = local_LZ4_decompress_safe_partial; dName = "LZ4_decompress_safe_partial"; break;
+ case 7: decompressionFunction = local_LZ4_decompress_safe_partial; dName = "LZ4_decompress_safe_partial"; checkResult = 0; break;
#ifndef LZ4_DLL_IMPORT
- case 8: decompressionFunction = local_LZ4_decompress_safe_forceExtDict; dName = "LZ4_decompress_safe_forceExtDict"; break;
+ case 8: decompressionFunction = local_LZ4_decompress_safe_forceExtDict; dName = "LZ4_decompress_safe_forceExtDict"; break;
#endif
- case 9: decompressionFunction = local_LZ4F_decompress; dName = "LZ4F_decompress";
+ case 9: decompressionFunction = local_LZ4F_decompress; dName = "LZ4F_decompress";
errorCode = LZ4F_compressFrame(compressed_buff, compressedBuffSize, orig_buff, benchedSize, NULL);
if (LZ4F_isError(errorCode)) {
DISPLAY("Error while preparing compressed frame\n");
@@ -589,9 +592,13 @@ int fullSpeedBench(const char** fileNamesTable, int nbFiles)
clockTime = clock();
while(BMK_GetClockSpan(clockTime) < TIMELOOP) {
for (chunkNb=0; chunkNb<nbChunks; chunkNb++) {
- int decodedSize = decompressionFunction(chunkP[chunkNb].compressedBuffer, chunkP[chunkNb].origBuffer, chunkP[chunkNb].compressedSize, chunkP[chunkNb].origSize);
- if (chunkP[chunkNb].origSize != decodedSize) DISPLAY("ERROR ! %s() == %i != %i !! \n", dName, decodedSize, chunkP[chunkNb].origSize), exit(1);
- }
+ int const decodedSize = decompressionFunction(chunkP[chunkNb].compressedBuffer, chunkP[chunkNb].origBuffer,
+ chunkP[chunkNb].compressedSize, chunkP[chunkNb].origSize);
+ if (chunkP[chunkNb].origSize != decodedSize) {
+ DISPLAY("ERROR ! %s() == %i != %i !! \n",
+ dName, decodedSize, chunkP[chunkNb].origSize);
+ exit(1);
+ } }
nb_loops++;
}
clockTime = BMK_GetClockSpan(clockTime);
@@ -604,8 +611,11 @@ int fullSpeedBench(const char** fileNamesTable, int nbFiles)
/* CRC Checking */
crcDecoded = XXH32(orig_buff, (int)benchedSize, 0);
- if (crcOriginal!=crcDecoded) { DISPLAY("\n!!! WARNING !!! %14s : Invalid Checksum : %x != %x\n", inFileName, (unsigned)crcOriginal, (unsigned)crcDecoded); exit(1); }
- }
+ if (checkResult && (crcOriginal!=crcDecoded)) {
+ DISPLAY("\n!!! WARNING !!! %14s : Invalid Checksum : %x != %x\n",
+ inFileName, (unsigned)crcOriginal, (unsigned)crcDecoded);
+ exit(1);
+ } }
DISPLAY("%2i-%-34.34s :%10i -> %7.1f MB/s\n", dAlgNb, dName, (int)benchedSize, (double)benchedSize / bestTime / 1000000);
}
diff --git a/tests/fuzzer.c b/tests/fuzzer.c
index 6c79515..b29e82e 100644
--- a/tests/fuzzer.c
+++ b/tests/fuzzer.c
@@ -504,7 +504,7 @@ static int FUZ_test(U32 seed, U32 nbCycles, const U32 startCycle, const double c
/* Test decoding with empty input */
FUZ_DISPLAYTEST("LZ4_decompress_safe() with empty input");
- LZ4_decompress_safe(NULL, decodedBuffer, 0, blockSize);
+ LZ4_decompress_safe(compressedBuffer, decodedBuffer, 0, blockSize);
/* Test decoding with a one byte input */
FUZ_DISPLAYTEST("LZ4_decompress_safe() with one byte input");
@@ -545,7 +545,6 @@ static int FUZ_test(U32 seed, U32 nbCycles, const U32 startCycle, const double c
ret = LZ4_decompress_safe(compressedBuffer, decodedBuffer, compressedSize, blockSize+1);
FUZ_CHECKTEST(ret<0, "LZ4_decompress_safe failed despite amply sufficient space");
FUZ_CHECKTEST(ret!=blockSize, "LZ4_decompress_safe did not regenerate original data");
- //FUZ_CHECKTEST(decodedBuffer[blockSize], "LZ4_decompress_safe wrote more than (unknown) target size"); // well, is that an issue ?
FUZ_CHECKTEST(decodedBuffer[blockSize+1], "LZ4_decompress_safe overrun specified output buffer size");
{ U32 const crcCheck = XXH32(decodedBuffer, blockSize, 0);
FUZ_CHECKTEST(crcCheck!=crcOrig, "LZ4_decompress_safe corrupted decoded data");
@@ -579,15 +578,16 @@ static int FUZ_test(U32 seed, U32 nbCycles, const U32 startCycle, const double c
FUZ_CHECKTEST(ret>=0, "LZ4_decompress_safe should have failed, due to input size being too large");
FUZ_CHECKTEST(decodedBuffer[blockSize], "LZ4_decompress_safe overrun specified output buffer size");
- // Test partial decoding with target output size being max/2 => must work
- FUZ_DISPLAYTEST();
- ret = LZ4_decompress_safe_partial(compressedBuffer, decodedBuffer, compressedSize, blockSize/2, blockSize);
- FUZ_CHECKTEST(ret<0, "LZ4_decompress_safe_partial failed despite sufficient space");
-
- // Test partial decoding with target output size being just below max => must work
- FUZ_DISPLAYTEST();
- ret = LZ4_decompress_safe_partial(compressedBuffer, decodedBuffer, compressedSize, blockSize-3, blockSize);
- FUZ_CHECKTEST(ret<0, "LZ4_decompress_safe_partial failed despite sufficient space");
+ /* Test partial decoding => must work */
+ FUZ_DISPLAYTEST("test LZ4_decompress_safe_partial");
+ { size_t const missingBytes = FUZ_rand(&randState) % blockSize;
+ int const targetSize = (int)(blockSize - missingBytes);
+ char const sentinel = decodedBuffer[targetSize] = block[targetSize] ^ 0x5A;
+ int const decResult = LZ4_decompress_safe_partial(compressedBuffer, decodedBuffer, compressedSize, targetSize, blockSize);
+ FUZ_CHECKTEST(decResult<0, "LZ4_decompress_safe_partial failed despite valid input data (error:%i)", decResult);
+ FUZ_CHECKTEST(decResult != targetSize, "LZ4_decompress_safe_partial did not regenerated required amount of data (%i < %i <= %i)", decResult, targetSize, blockSize);
+ FUZ_CHECKTEST(decodedBuffer[targetSize] != sentinel, "LZ4_decompress_safe_partial overwrite beyond requested size (though %i <= %i <= %i)", decResult, targetSize, blockSize);
+ }
/* Test Compression with limited output size */